Thermodynamics : ATPFromGlucose (8 Variations)
When glucose is oxidized in the human body it releases a lot of Gibbs free energy. Rather than waste this free energy, the body stores much of it in the form of ATP. The following reaction shows this process of storing some of the energy from glucose in ATP. This is an example of coupled reactions in a biological system.
The label on a can of Coke says that it contains 39 g of sugar. Assume that all of the sugar is glucose (even though it isn't), and calculate how many moles of ATP can be produced theoretically by the oxidation of 39.0 g of glucose.

Thermodynamics : GibbsFromHSandT (5 Variations)
On the space shuttle, the carbon dioxide produced by the astronauts is handled by an environmental control system that utilizes the following reaction.H° = -138.4 kJ and S° = -139 J/K
Calculate G° at 25°C for this reaction.

Thermodynamics : EntropyPhaseChange (13 Variations)
Aluminum can be evaporated in a vacuum to form highly reflective coatings. Aluminum boils at 2792K and has a heat of vaporization of 70.0 kcal/mol. Calculate the entropy change for the vaporization of one mole of aluminum.

Thermodynamics |

Chemometrics |

Phases / Phase Transitions / Diagrams

Thermodynamics : ProbabilityEnergyDist (23 Variations)
Consider a system that has two indistinguishable molecules that can occupy three different energy levels (having energies of 1kJ, 2kJ and 3kJ, respectively). What is the probability that the molecules will have a total energy of 2 kJ?

Gases : VolGasReactInTorch (10 Variations)
Oxyacetylene torches used in high-temperature welding use a combination of oxygen and acetylene. The combustion of acetylene (C2H2) occurs in these torches. What volume of oxygen is needed to react with 250 mL of acetylene?

Bonding : ImpossibleStructure (10 Variations)
Which of the following formulas represent substances that are likely to be stable at ordinary temperature and pressure? A good way to decide is to ask for which of the formulas is it possible to draw a reasonable Lewis structure (one that obeys the usual rules for drawing Lewis structures)?

Lewis Structures |

Covalent Bonding

Thermochemistry : HeatCapacityLiq (4 Variations)
100 g of water (c=4.184 J/g.oC), 100 g of ethanol (c=2.46 J/g.oC), 100 g of carbon tetrachloride (c=0.861 J/g.oC), and 100 g of ethylene glycol (c=2.42 J/g.oC) at 50oC were each placed into a separate coffee cup calorimeter and the temperature recorded. The temperature of the surroundings was 20oC. After one hour the temperature of which substance would have changed by the largest amount? Assume that the rate of heat transfer from the coffee cup to the surroundings was the same in each case.

Calorimetry / Thermochemistry |

Heat Capacity

Gases : GasRxnVolumes (10 Variations)
A gas phase reaction takes place in a syringe at a constant temperature and pressure. If the initial volume before reaction is 30 mL and the final volume after the reaction is complete is 15 mL, which of the following reactions took place? (Note: You can assume that you start with stoichiometric amounts of the reactants, the reaction goes to completion and that the gases behave ideally.)

Equilibrium : CalcRxnQuotient (13 Variations)In an experiment, 4.44 mol of SO2, 7.93 mol of O2 and 4.03 mol of SO3 are placed in a 2.0L reaction vessel at a certain temperature. Calculate the reaction quotient, Q, for the reaction as written:

What is the calculated reaction quotient, Q? {2:NUMERICAL:=2.1e-1:1e-2#Correct! ~%50%2.1e-1:5e-2#Close but not quite right}

If Kc for this reaction at the temperature of the experiment is 3.7 x 103, will the reaction move toward the left or toward the right? {1:MULTICHOICE:left#Sorry, that's wrong.~=right#Correct!}

Equilibrium |

Chemometrics

Gases : GasLaws (2 Variations)
Note: This is a calculation type question. If you exit the quiz without submitting it and you do not save an answer before exiting the quiz, the values in the question may change when you enter the quiz again.

You purchase a propane tank that can hold gas safely up to a pressure of {x} atm. When the tank contains 100. grams of propane at {y}°C, the gas exerts a pressure of {z}atm. What is the highest temperature to which the propane can be heated safely? (Report your answer in Kelvins.)

Gases |

Chemometrics

Kinetics : ArrheniusTemp (3 Variations)
The activation energy for the isomerization of cyclopropane to propene is 274 kJ/mol. By what factor does the rate of reaction increase as the temperature rises from 500oC to 550oC assuming all else remains constant? (R = 8.314 J/mol k)

Hint: This is asking for the ratio of rates which is proportional to the ratio of the rate constants, all else being equal.

Kinetics |

Chemometrics

Thermochemistry : BombCalorimeter (4 Variations)
Stearic acid (CH3(CH2)16CO2H) is a fatty acid, the part of fat that stores most of the energy. 1.00 g of stearic acid was burned in a bomb calorimeter. The bomb had a heat capacity of 652 J/oC and a 500. g water reservoir. If the temperature rose from 25.0 to 39.3 oC, how much heat was released when the stearic acid was burned?

Calorimetry / Thermochemistry |

Chemometrics

Thermochemistry : CoffeeCupCalorimeter (2 Variations)
A block of copper is heated to {x} °C and then is dropped into a coffee cup calorimeter containing {y} g of water at 25.0 °C. The final temperature of the system is 45.1 °C. What is the mass of the copper block to the nearest gram? (Assume all heat is transferred to the water). Write your answer in the box, and do NOT include units.

Specific heat capacity of copper = 0.383 J/(g*°C)

Specific heat capacity of water = 4.18 J/(g*°C)

Calorimetry / Thermochemistry |

Chemometrics

Gases : GasRxnStoich (10 Variations)
One of the reactions in the process of obtaining very pure silicon for the microelectronics industry is shown below. If 24 g of SiO2 is reacted with an excess of carbon, what volume of gaseous carbon monoxide will be produced at a temperature of 17oC and a pressure of 735 mm Hg?

What will happen to the concentration of CO2 if the temperature is increased?

Equilibrium

Equilibrium : RxnDirectAndTemp (16 Variations)
2 SO2(g) + O2(g)
2 SO3(g)
The reaction above has an equilibrium constant of 0.25 at 830oC, and Horxn = -197.78 kJ/mol under standard conditions. Under which conditions will this reaction produce the most sulfur trioxide?

Equilibrium

Equilibrium : CalcKc (4 Variations)
A container initially has {y} M ammonia at a certain temperature. When the system reaches equilibrium the concentration of ammonia is {x} M. Calculate Kc for the following reaction as written.

Note:
Answers must be written using scientific notation with "e"
DO NOT use spaces
DO NOT write in the units.
Be sure to use three significant figures.
eg: 2.44e-5

In an experiment, 50 g of a metal was heated to 100oC and placed in 200 g of a liquid at 25oC. Which of the following combinations of metal and liquid will produce the largest temperature increase in the liquid? (Assume that there is no transfer of energy to the surroundings.)

In an experiment a block of aluminum was heated to 100oC and placed in 200 g of water at 25oC. If the final temperature of the system is 43oC, and no heat transfer to the surroundings occurred, what is the mass of the aluminum block?